This invention relates to a composite lithographic printing plate and method therefor. More particularly, this invention relates to a lithographic printing plate system which greatly reduces the cost involved in printing, for example, using offset or direct litho (di-litho) printing presses and aluminum base printing plates.
Aluminum base lithographic printing plates, such as described in my U.S. Pat. No. 3,181,461 issued May 4, 1965, have come into wide use in the printing industry and especially in lithographic printing using offset and di-litho printing presses. This use is increasing with the conversion of letterpress printing presses for newspapers to di-litho systems where printing is carried out with direct contact between the printing plate and the newsprint.
Aluminum base plates are attractive because they offer durability, long press runs and reproducible, reliable quality printing. However, cost is a factor and even though used aluminum printing plates can be recycled, the cost compared to the relatively short period of use is still high. This applies to both wipe-on and presensitized lithographic printing plates.
The present invention provides a lithographic printing plate system that retains all of the benefits and advantages gained through the use of an aluminum printing member yet greatly reduces the cost involved.